Glaucoma is a leading cause of blindness world-wide. Chronic primary open-angle glaucoma is the most common form among Caucasian patients. The key feature of glaucoma is damage to the optic nerve head, which is not necessarily related to an increased intraocular pressure. The prevalence of glaucoma among the patients with sleep apnoea was 7,2%: normal-tension glaucoma 2,9%, primary open-angle glaucoma 4,3%. The prevalence of obstructive sleep apnoea syndrome (OSAS) is around 4-10% for men and 2-4% for women. Matrix metalloproteinases (MMPs) substrates include essentially all extracellular matrix components as well as a wide array of molecules involved in intracellular adhesion, cell-matrix interaction, and cell signalling. However, MMPs effects are not restricted to extracellular matrix degradation. The prevalence of increased MMP in patients with OSAS and its predicting value for an additional glaucoma are not known. Further, we do not know if treatment of OSAS with nasal continuous positive air pressure(nCPAP) can decrease the MMP activity. With this study, we want to determine the prevalence of MMP activity and the prevalence of glaucoma in patients with OSAS. Further, we want to investigate if a nCPAP treatment period of four weeks decreases the MMP activity.